Antimicrobial Activity of Cinnamomum cassia Essential Oil: Phytochemical Profiling, In Vitro Evaluation, and Molecular Docking.

In this study, Cinnamomum cassia bark essential oil (CEO) was extracted with a yield of 2.51% and characterised by its organoleptic properties, physicochemical characteristics, and gas chromatography-mass spectrometry (GC-MS) profiling. Seven phytoconstituents were identified, with (E)-cinnamaldehyde predominating (87.14%). CEO inhibited Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 27853, with inhibition zones of 16.0 ± 1.0-47.0 ± 1.0 mm. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values ranged from 0.52-1.04 and 0.52-2.08 mg/mL, respectively, with greater susceptibility observed among the gram-positive strains. Antifungal evaluation revealed potent activity against Alternaria alternata and moderate activity against Aspergillus niger, with direct-contact exposure showing greater inhibition of As. niger than vapour-phase treatment. Molecular docking identified coumarin, a minor constituent, as exhibiting the strongest predicted binding, with binding energies of -7.7 kcal/mol against the bacterial targets TEM-1 β-lactamase and D-alanine:D-alanine ligase, and -7.0 kcal/mol against tyrosyl-tRNA synthetase. Coumarin also showed favorable predicted binding to the fungal targets cytochrome P450 51B (CYP51B) and epoxide hydrolase. These findings support the potential of CEO as a natural antimicrobial preservative, although further validation in real food systems is required.